The Mufti of The Kingdom of Saudi Arabia, Shaykh Abdul Azeez bin Abdullaah aal ash-Shaykh (may Allaah preserve him) was asked the following question:
Q: If the day of Arafah (the 9th of Dhul-Hijjah) was to coincide with Friday is it permissible to single it out with fasting (i.e. by not fasting a day along with it)? May Allaah reward you with good.
A: Fasting Friday is forbidden if the intent is the day of Friday itself – i.e. singling out the day of Friday; so one must fast a day before it or a day after it.
As for it (Friday) coinciding with a day that is obligatory to fast, or (if Friday coincided) with fasting the six days of Shawwaal, or with fasting the ninth or tenth day of Muharram, or with fasting the day of Arafah – then there is nothing to prevent him from that (fasting Friday by itself); as long as he is not in a state of Ihraam performing Hajj.
[Source: The Official Website of the Mufti of the Kingdom of Saudi Arabia – http://www.mufti.af.org.sa/node/2886 ]